The present invention relates to a system for use with an abandoned well of a subterranean formation containing a well bore. More particularly, the present invention relates to a rigless system for operationally supporting an apparatus designed for cutting an underwater casing.
In the production of oil and gas in subterranean formations, it is often found that a well bore that penetrates the subterranean formation must be plugged and abandoned. The plug and abandonment operations are expensive; they involve the use of valuable offshore rig space, operation of rig-mounted pedestal cranes and other platform-mounted equipment.
Conventionally, the casings are severed by an explosive charge delivered underwater to a desired depth below the bed of the body of water and detonated. However, the explosives are harmful to marine life and to the surrounding water. Additionally, the residual oil and gas may leak into the surrounding water, which raise serious concerns of contamination in that area.
As an alternative to the explosive cutting methods, the industry has developed cutting techniques that provide for the use of mechanical cutting tools activated from the surface for cutting the casing below the mud line. The majority of the tools use rig-mounted equipment, which necessitates the presence of an offshore platform in the well bore location. Some of the cutting tools are connected to an operational system suspended from a pedestal crane, and the vibrations created by the cutting operations are transmitted to the crane. Often times, the vibrations are so strong that the pedestal crane becomes unbalanced and topples. As a consequence, less powerful cutting tools have to be used, which increases the casing cutting time
The present invention contemplates elimination of problems associated with convention techniques and provision of a rigless support apparatus that can be easily transported to the site of the well plug-and-abandon operation for supporting the underwater operations offshore.